This invention relates to heater-cathode assemblies and more particularly to such assemblies which have fast warm-up characteristics and are suitable for use in cathode ray tubes of the type employed in television receivers.
The cathodes conventionally used in such tubes have a warm-up time of 12 to 15 seconds; that is, it requires that long a time for sufficient electrons to be present from the cathode to be drawn to the anode and establish a viewable raster on the screen of the tube.
Previously used fast warm-up cathodes (with warm-up time from 3.5 to six seconds) have employed various modifications of conventional cathodes such as are shown in U.S. Pat. Nos. 3,881,124; 3,947,715; 3,958,146 and 4,009,409 or they have employed complicated and expensive structures.
However, it is believed it would be an advance in the art to provide a simple and economical cathode with warm-up times faster than those heretofore achieved.